The motif of these 36-centimeter-long relics seems to have been taken from a bird based on the way their edges have been shaped to resemble bird feathers. The three pieces once decorated a gilt bronze crown. The missing top part of the piece in the center leaves its original form a mystery, while the two other pieces on either side are symmetrical to one another.
The Koguryo crown decorations are assumed to have been produced while the ancient Korean kingdom developed relations with the cultures of Northern Yan and other nomadic tribes in northeastern China. The people of Koguryo considered birds as spiritual beings that traveled between this life and the next, which meant they were guides necessary in leading the dead to the afterworld.
The bird feather-shaped decorations hint at the belief the people of Koguryo had in afterlife as well as at their Taoist view of the world.
Reference: National Museum of Korea